Whenever you set up your project settings, they remain your 'default' project settings until you change them.

But your default project settings have nothing to do with the timeline. You can't open a project and have the timeline already filled in with title clips.

Although you could create a project with those titles on your timeline and use it as a template, starting out with that pre-loaded project and doing a Save As every time you start a new project.

But there's no such thing as a default output setting. Your Publish & Share settings are whatever you select. (Although, as I show you in my book, you can create a preset for a custom output and have that be available whenever you choose a certain output format.)